1. Field of the Invention
The present invention relates to an electrophotographic member, a process cartridge, and an electrophotographic apparatus.
2. Description of the Related Art
An electrophotographic apparatus adopting an electrophotographic system mainly includes an electrophotographic photosensitive member, a charging device, an exposing device, a developing device, a transferring device, and a fixing device. The charging device adopts a system of charging a surface of an electrophotographic photosensitive member by applying a voltage (only a DC voltage or a DC voltage superimposed with an AC voltage) to a charging member disposed so as to be brought into contact or proximity with the surface of the electrophotographic photosensitive member. From the viewpoints of performing charging stably and reducing generation of ozone, a contact charging system of performing charging with a charging member in contact with a surface of an electrophotographic photosensitive member has been preferably used. In the case of the contact charging system, a roller-shaped charging member (hereinafter referred to as “charging roller” has been preferably used.
In the case of using the charging roller in the contact charging system, there is a problem in that a horizontal stripe-like uneven charging image is liable to be formed owing to minute resistance unevenness of the charging member and contamination of a surface of the charging member with toner and an external additive.
In order to solve the above-mentioned problem, various attempts have been made. As one of those attempts, there has been proposed a method involving improving a horizontal stripe-like uneven charging image by incorporating resin particles into a resin layer of a charging roller to form convex portions, thereby uniformizing charging (Japanese Patent Application Laid-Open No. 2003-316112).
Further, as particles for forming the convex portions, composite particles including a spindle-shaped, a cylinder-shaped, or a needle-shaped insulating material as base particles carrying a metal oxide on a surface thereof are used. There has been proposed a method involving improving a defective image caused by contamination and a defective image caused by discharge defects by forming small to large convex shapes using the particles (Japanese Patent Application Laid-Open No. 2009-9029).